ZnO film formation using a steered and shielded reactive vacuum arc deposition

Abstract

Zinc oxide (ZnO) thin films were prepared on a borosilicate glass substrate by a steered and shielded reactive vacuum arc deposition method. The cathode spot was driven on a cathode surface using weak and strong permanent magnets, placed behind the cathode. The radial magnetic flux densities at the bottom of cathode shoulder were 1.0 mT and 5.5 mT, respectively. The arc was operated at DC 30 A and the in-process pressure was varied from 0.1 to 5.0 Pa. No bias was applied to the substrate. The substrate temperature was below 75°C after 20-min deposition. The deposition rate increased with the in-process pressure until 1.0 Pa with both weak and strong magnets. X-Ray diffraction analysis revealed that all films had a strong ZnO (200) peak, indicating c-axis orientation. In particular, the films strongly oriented to (200) were obtained at 0.5–3.0 Pa for the strong magnet. Highly transparent films in visual region were obtained at 0.5 and 3.0 Pa with both weak and strong magnets. A refractive index at 600 nm varied from 1.75 to 1.95. With the strong magnet, electric resistivity varied from 10 −3 to 15 Ω cm as the pressure increased. However, with the weak magnet, resistivity of the order of 10 −3 Ω cm was obtained over a wide pressure range of 0.1–1.0 Pa.